This application claims the benefit of the Korean Application No. P2001-88452 filed on Dec. 29, 2001, which is hereby incorporated by reference for all purposes as if fully set forth herein.
1. Field of the Invention
The present invention relates to liquid crystal displays and a method for fabricating the same, and more particularly to a liquid crystal display and a method for fabricating a liquid crystal display, wherein adhesive characteristics of a sealant arranged between two substrates is enhanced.
2. Background of the Related Art
Compared to cathode-ray tubes (CRTs), flat panel displays (e.g., liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), etc.) display high quality images, consume a relatively low amount of power, produce a low amount of heat, and may be fabricated in small sizes. Due to these characteristics, LCDs in particular are extensively used in devices such as watches, calculators, personal digital assistants (PDAs), cellular phones, notebook computers, monitors for personal computers (PCs), televisions, TV receivers, monitors in airplanes, etc.
LCDs typically include a liquid crystal display panel for displaying a picture and a driving circuit for providing driving signals to the liquid crystal display panel. The liquid crystal display panel includes first and second glass substrates bonded to, and spaced apart from each other by a cell gap into which a layer of liquid crystal material is injected.
The first glass substrate (i.e., the TFT array substrate) supports a plurality of gate lines arranged at a fixed interval and oriented along a first direction, a plurality of data lines arranged at a fixed interval and oriented along a second direction, perpendicular to the first direction, a plurality of pixel electrodes arranged in a matrix pattern at pixel regions where the plurality of gate and data lines cross each other, and a plurality of switching devices (e.g., thin film transistors) responsive to signals supplied from gate lines for switching signal supplied from corresponding data lines and for transmitting the switched signals to corresponding pixel electrodes.
The second glass substrate (i.e., the color filter substrate) supports a black matrix layer for shielding light from parts excluding the pixel regions, an RGB color filter layer for transmitting light at predetermined wavelengths to thereby display colors, and a common electrode.
The first and second substrates are bonded together with sealant, the cell gap is maintained by spacers, and the layer of liquid crystal material is injected into the cell gap between the two substrates.
Sealants are typically provided as thermosetting or photosetting sealants. Typical thermosetting sealants are formed of a mixture of an epoxy resin and an amine or an amide curing agent. Thermosetting sealants are capable of bonding the two substrates when heated at approximately 100xc2x0 C. for about one hour. Typical photosetting sealants include UV photosetting sealants and are formed of a mixture of an acrylate resin and a photosetting agent capable of forming radicals when exposed to UV light. Photosetting sealants are capable of bonding the two substrates when exposed to UV light for approximately 30 seconds.
The aforementioned sealants have excellent adhesive characteristics when bonded to glass substrates, but relatively poor adhesive characteristics when bonded to organic films. Nonetheless, organic films are used as protection films in reflective or semi-transmissive LCDs and in providing large aperture LCDs. In order to enhance the adhesive characteristics of sealants within large aperture LCDs containing an organic protection film, a portion of the organic protection film located under where the sealant is to be formed is removed. Accordingly, the sealant may contact the glass substrates and bond the two substrates together via strong adhesive characteristics.
FIG. 1 illustrates a related art LCD and a method for fabricating the LCD.
Referring to FIG. 1, though not shown, the first glass substrate 100 supports a plurality of gate lines arranged at a fixed interval and oriented along a first direction, a plurality of data lines arranged at a fixed interval and oriented along a second direction, perpendicular to the first direction, a plurality of pixel electrodes arranged in a matrix pattern at pixel regions where the plurality of gate and data lines cross each other, and a plurality of switching devices (e.g., thin film transistors) responsive to signals supplied from gate lines for switching signal supplied from corresponding data lines and for transmitting the switched signals to corresponding pixel electrodes.
Though not shown, the second glass substrate 150 supports a black matrix layer 130 for shielding a light from parts excluding the pixel regions, an RGB color filter layer for transmitting light at predetermined wavelengths to thereby display colors, and a common electrode.
A sealant 110 is coated on a periphery of the first or second glass substrate 100 or 150 for bonding the two substrates together. The black matrix layer 130 is arranged between an active display region 120 and the sealant 110.
Referring to FIG. 1, the first glass substrate 100 is formed larger than the second glass substrate 150 and a plurality of gate PAD connection lines 103 and a plurality of data PAD connection lines 104 are formed for applying signals to the plurality of gate and data lines, respectively.
Components are mounted on gate and data PCBs 105 and 106, respectively, are formed outside the first substrate 100. The components on the PCBs generate input signals (e.g., control signals, power signals, data signals, etc.) to a gate driver IC 107a and a data driver IC 107b included within gate and data TCPs 101 and 102, respectively. The gate and data driver ICs 107a and 107b, respectively, provide voltages to the gate and data lines, respectively. Connected to the gate PAD connection lines 103 and the data PAD connection lines 104, the gate and data TCPs 101 and 102 receive signals from the gate PCD 105 and the data PCB 106, respectively, and provide signals to the gate and data lines.
FIG. 2A illustrates a sectional view of area xe2x80x9cExe2x80x9d shown in FIG. 1. FIG. 2B illustrates a back side view of the first glass substrate 100 having the sealant, PAD connection lines, and protection film coated thereon in area shown in FIG. 2A.
As described above, adhesive characteristics of the sealant are greater with respect to glass substrates than to organic films. In order to enhance adhesive characteristics between bonded substrates including an organic protection film 108, a portion of the organic protection film 108, located under where the sealant 110 is to be formed, is removed thereby allowing the sealant 110 to directly contact the first glass substrate 100.
Referring to FIGS. 2A and 2B, the gate PAD connection lines 103 are formed on the first glass substrate 100 and the data PAD connection lines 104 are formed on a gate insulating film (not shown) also formed on the first glass substrate 100. The organic protection film 108, being an insulating film, is formed over an entire surface of the first substrate 100, including the gate and data PAD connection lines 103 and 104.
The gate insulating film (not shown) and the organic protection film 108 are is selectively removed to expose portions of the first glass substrate 100 between the gate and data PAD connection lines, thereby forming opened areas 109. The sealant 110 is then coated on the organic protection film 108 such that the sealant 110 directly contacts the first glass 100 substrate at the opened areas 109.
Since thermosetting and photosetting sealants have better adhesive characteristics with glass substrates compared to the organic protection film 108, the opened area 109 allows the sealant 110 to directly contact the first glass substrate 100 and maximize the adhesive characteristics of the LCD device.
However, use of the aforementioned LCD fabricating method is disadvantageous for the following reasons.
First, the sealant is coated over the entire substrate including over the gate and data PAD connection lines formed of different materials, at different times, and under different fabricating conditions. The etching rate of the protection film is dependent upon the materials and patterns over which the protection film is formed. Accordingly, the uniformity of the cell gap between the first and second glass substrates may be reduced and blots are formed on the LCD.
For example, the gate PAD connection lines are spaced from each other at greater intervals than the data PAD connection lines. Accordingly, the size of the opened areas 109 between the gate PAD connection lines is larger than the size of the opened areas 109 between the data PAD connection lines. Further, depending on the location of the PAD connection lines, different types of connection lines may be further included within the gate or data PAD connection lines. As a result, when a uniform amount of sealant is coated on the opened parts 109, a height of the sealant 110 coated between the gate PAD connection lines is lower than a height of the sealant 110 coated between the data PAD connection lines and a non-uniform cell gap is created between the two glass substrates.
Second, as the resolution of LCDs increases, the distance between the PAD connection lines decreases. Accordingly, design of the opened areas becomes difficult.
Accordingly, the present invention is directed to an LCD and a method of fabricating an LCD that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An advantage of the present invention provides an LCD and a method for fabricating an LCD, wherein adhesive characteristics of the sealant are maximized while the uniformity of the cell gap is maintained.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. These and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the liquid crystal display (LCD), may include first and second glass substrates bonded together by a sealant, PAD connection lines arranged on the first substrate, a protection film arranged over an entire surface of the first substrate including the PAD connection lines, wherein a portion of the protecting film, located under where the sealant is to be formed, is removed.
In one aspect of the present invention, a portion of the protection film is removed to a predetermined thickness.
In another aspect of the present invention, a portion of the protective film is removed between the PAD connection lines to form opened areas exposing the substrate between the PAD connection lines.
In still another aspect of the present invention, a method for fabricating an LCD may include steps of providing a substrate, forming PAD connection lines on the substrate, forming a protection film over the entire surface of the first substrate including the PAD connection lines, patterning portions of the protection film located under where sealant is to be coated such that the protection film is formed to a predetermined thickness over the PAD connection lines, and coating the sealant over the patterned portions of the protection film.
In yet another aspect of the present invention, a method for fabricating an LCD may include steps of providing a substrate, forming PAD connection lines on the substrate, forming a protection film over the entire surface of the first substrate including the PAD connection lines, patterning portions of the protection film located under where sealant is to be coated such that the protection film is formed to a predetermined thickness over the PAD connection lines and also such that the substrate is exposed between the PAD connection lines, and coating the sealant over the patterned portions of the protection film.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.